1. Field of the Invention
This invention relates to an automatic transmission for a motor vehicle that includes planetary gearsets and clutches and brakes state of engagement and disengagement determines operative speed ratios produced by the transmission.
2. Description of the Prior Art
In a front wheel drive vehicle, the axial space available for the transmission is limited by the width of the engine compartment and the length of the engine. In addition, the trend to increase the number of ratios available generally increases the number of components required. For these reasons, it is desirable to position components concentrically in order to minimize axial length. The ability to position components concentrically is limited, however, by the need to connect particular components mutually and to the transmission case.
Furthermore, it is desirable for the output element to be located near the center of the vehicle, which corresponds to the input end of the gear box. An output element located toward the outside of the vehicle may require additional support structure and add length on the transfer axis. With some kinematic arrangements, however, the need to connect certain elements to the transmission case requires that the output element be so located.
A transmission requires a compact transfer shaft support design. A need exists for a transfer gear assembly, which requires no bearing support for the transfer shaft, and a ball bearing, rather than thrust bearings, to react thrust forces in both axial directions. The transfer gear teeth are preferably helical teeth.